<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button id="hmd">湖北民族大学logo</button>
    <button id="zmd">中央民族大学logo</button>
    <br>
    <img src="../images/logob.png" alt="" title="湖北民族大学">

    <script>
        
        var hmd = document.getElementById('hmd');
        var zmd = document.getElementById('zmd');
        var img = document.querySelector('img');

        zmd.onclick = function() {
            img.src = '../images/logo.png';
            img.title = '中央民族大学';
        }

        hmd.onclick = function() {
            img.src = '../images/logob.png';
            img.title = '湖北民族大学';
        }
      
    </script>
    
</body>
</html>